Technical Field
The present invention relates to optical sensing systems, and more particularly, systems and methods for cleaning open path optical sensing systems.
Description of the Related Art
Optical sensing systems are utilized for a wide range of applications including gas and particle sensing and detection. One type of optical particle sensing and detection is open path absorption spectroscopy. In open path absorption spectroscopy, an optical source and a receiver are placed in the same environment as a gas to be measured. A light, such as a laser or LED, is directed by the optical source directly through the gaseous environment. The different types of gases in the environment will cause the light to absorb at different wavelengths. The absorbed light is received by the receiver and is measured and analyzed to discover the type of gases that are present and their respective concentrations.
Examples of open path absorption spectroscopy systems, include Tunable Diode Laser Absorption Spectroscopy (TDLAS), Intra-Cavity Absorption Spectroscopy (ICAS), and Cavity-Ring Down Spectroscopy (CRDS).
A main disadvantage of open path absorption spectroscopy is that the surfaces of some optical components are exposed to environmental pollutants which lead to a degradation of the performance of the system. For example, the optical components may exhibit a poorer reflection, poorer transparency or a sensor malfunction due to the environmental pollutants. Prior art systems have been provided with higher quality surface materials and an improved build quality in order to reduce potential pollutants from contacting the surface of the system. However, these systems have only provided marginal benefits with respect to the accumulation of pollutants.
Other prior art systems have featured mechanical wiping mechanisms, such as wipers, that are configured to wipe pollutants from the surface of the optical components. However, the mechanical wiping mechanisms are susceptible to inadvertently damaging the optical components and may also affect the performance of the sensor. Furthermore, the mechanical wiping mechanisms require continual replacement.
Other prior art systems have been developed which wash the surface of the optical components in order to remove pollutants. For example, a stream of washer fluid may be directed onto the surface of an optical component and the surface may be rotated. The surfaces of the washed components are then dried. However, in these systems, the sensors are unable to function during the cleaning and drying periods. The cleaning solution may also leave a residue which can degrade the performance of the optical system. Furthermore, these systems require additional structures to operate, such as electrical power and a water supply.
Therefore, a system and method for cleaning open path optical sensors which effectively cleans the optical component surfaces and prevents a build-up of pollutants which does not damage the surface of the optical component, does not require replacement of parts that are subject to frequent degradation, does not require the use of a cleaning fluid, and allows constant operation of the optical sensor would be highly advantageous.